(a) Field of the Invention
The present invention relates to a link antenna of an in-building radio frequency (RF) repeater, and in particular, relates to a method for selecting the installation position of a link antenna of an in-building RF repeater and a cable device and a terminal thereof.
(b) Description of the Related Art
In general, radio waves generated by a base station in a mobile communication system do not easily reach inner spaces of large buildings, rear parts of mountains or hills, tunnels, or subways, and hence, these areas may cause calling problems to mobile communication. Therefore, blanket areas are generated because of the position of base station or geographical problems. In order to solve the blanket areas, cheap repeaters that cover the blanket areas with weak radio waves are currently used. Particularly, an in-building RF repeater solves the problem of blanket area in the building, and as shown in FIG. 1, a donor unit 5 is installed in the outer part of a building 3, particularly a rooftop, and a remote unit 9 that is connected to the donor unit 5 through a coaxial cable 7 is installed within the building 3 so that the mobile communication service may be provided within the building. In this instance, the donor unit 5 transmits and receives radio signals to/from the base station 1 so that the donor unit 5 and the remote unit 9 form an in-building RF repeater.
Here, in the in-building RF repeater, an RF antenna for transmitting and receiving RF signals to/from the base station 1 is called a link antenna, and the Yagi antenna is generally used. The Yagi antenna is invented by two Japanese, Yagi and Unoda, and is a directional beam antenna that is most frequently used recently. Since the link antenna for the in-building RF antenna has directivity, the direction of the link antenna is an important factor that directly controls the efficiency of the mobile communication service. Also, a patch antenna, a sector antenna, and a parabolic antenna in addition to the Yagi antenna are applicable to the link antenna.
A general mobile communication terminal displays various terminals states to the user so that he may know the terminal states at a specific mode wherein the terminal states include the received signal strength indication (RSSI) and the energy per chip over interface noise (Ec/Io).
Therefore, when an in-building RF repeater is installed conventionally, an installer can use Ec/Io information displayed on the terminal when he determines the position for installing a link antenna on the rooftop of a building.
That is, the installer of a link antenna selects the position at which the link antenna will be installed while viewing the information such as RSSI and Ec/Io displayed on a terminal that provides a mobile communication service on the rooftop of the building.
The installer installs the link antenna and connects the coaxial cable 7 connected to the remote unit 9 installed within the building to a feeding cable of the link antenna to thus install the in-building RF repeater.
Another installer in the building communicates with the installer outside the building and selects the optimized direction of the link antenna while checking the Ec/Io displayed on the terminal for receiving a mobile communication service through the remote unit 9.
The above-noted process is the optimized method for installing the link antenna of the in-building RF repeater in the prior art.
However, since signals transmitted by a plurality of sectors (i.e., pseudo noise (PN)) are provided on the outside of the building where the link antenna is installed, that is, the rooftop, it is not allowed to select the optimized position by using the information (i.e., Ec/Io) measured from a mobile terminal having an omni-directional antenna when selecting the position for selecting the link antenna. That is, the problem occurs because the position is selected by using a general mobile communication terminal having an omni-directional antenna that is different from the link antenna's RF pattern.
Further, since it is required to manually select the direction of the link antenna by calling another installer who is positioned in the building after the link antenna is installed at the position that is not optimized or after the same is incidentally installed at the optimized position, a log time is needed to finish installation on the link antenna and the cost of installation and maintenance on the link antenna is increased since at least two installers are needed.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.